Method for operating a charging arrangement for charging a high-voltage battery of an electrically powered vehicle

Abstract

The invention relates to a method for operating a charging arrangement (1) for charging a high-voltage battery (2) of an electrically powered vehicle at a charging station (3) with direct current, wherein the charging arrangement (1) has a first charging path (4) for use when charging at a charging station (3) that supplies a voltage (V_EVSE) equal to the nominal voltage of the high-voltage battery (2), wherein the charging arrangement (1) further has a second charging path (5) for use when charging at a charging station (3) that supplies a voltage (V_EVSE) lower than the nominal battery voltage, wherein a voltage converter (6) is arranged in the second charging path (5) which is configured to increase the lower voltage (V_EVSE) of the charging station (3) to the level of the nominal battery voltage, wherein the voltage converter (6) in the second charging path (5) when charging at a charging station (3) that supplies a voltage (V_EVSE) equal to the nominal battery voltage,to increase the charging current in addition to the first charging path (4), wherein a voltage gain of the voltage converter (6) is at least almost exactly 1 and a current (I_Booster) in the second charging path (5) is regulated to a defined target current.

Description

[0001] The invention relates to a method for operating a charging arrangement for charging a high-voltage battery of an electrically driven vehicle according to the preamble of claim 1.

[0002] It is known to use a charging arrangement for charging a high-voltage battery of an electrically driven vehicle at a charging station with direct voltage, which charging arrangement has a first charging path for use when charging at a charging station which supplies a voltage equal to a nominal battery voltage of the high-voltage battery, and which further has a second charging path for use when charging at a charging station which supplies a voltage which is lower than the nominal battery voltage, wherein a voltage converter is arranged in the second charging path and is configured to raise the lower voltage of the charging station to the level of the nominal battery voltage.

[0003] When charging at a charging station with the battery's nominal voltage, the charging current may be limited by the dimensioning of components in the first charging path, such as cables, connectors, contactors, and busbars. These components may be undersized for cost or space reasons.

[0004] The generic document DE 10 2020 007 867 A1 describes a method for charging an energy storage device of a vehicle, wherein - a charging process of the energy storage device is carried out using a charging device of the vehicle, - in a first phase of the charging process, the storage energy source is charged with a first direct voltage of the charging source corresponding to a charging current of the charging source, - a battery voltage of the stored energy source is determined during the charging process, - the battery voltage of the stored energy source is compared with the charging voltage of the charging source, - a voltage converter is operated according to the comparison of the battery voltage with the charging voltage, - wherein in a second phase of the charging process following the first phase, the stored energy source is charged with a second DC voltage of the voltage converter corresponding to a choke current of the voltage converter.

[0005] The invention is based on the object of providing a novel method for operating a charging arrangement for charging a high-voltage battery of an electrically driven vehicle.

[0006] The object is achieved according to the invention by a method for operating a charging arrangement for charging a high-voltage battery of an electrically driven vehicle having the features of claim 1.

[0007] Advantageous embodiments of the invention are the subject of the subclaims.

[0008] A method is proposed for operating a charging arrangement for charging a high-voltage battery of an electrically driven vehicle at a charging station with direct voltage, wherein the charging arrangement has a first charging path for use when charging at a charging station which supplies a voltage equal to a nominal battery voltage of the high-voltage battery, wherein the charging arrangement further has a second charging path for use when charging at a charging station which supplies a voltage which is lower than the nominal battery voltage, wherein a voltage converter is arranged in the second charging path and is configured to raise the lower voltage of the charging station to the level of the nominal battery voltage.

[0009] According to the invention, the voltage converter in the second charging path is operated in addition to the first charging path when charging at a charging station which supplies a voltage equal to the nominal battery voltage in order to increase the charging current, wherein a voltage gain of the voltage converter is at least almost exactly 1 and a current in the second charging path is regulated to a defined target current.

[0010] By additionally operating the voltage converter during DC charging at the battery's nominal voltage, the charging power can be increased, or alternatively, the current-carrying components in the first charging path can be reduced in their current-carrying capacity by the value of the current in the second charging path. This is particularly noticeable in the cable cross-sections of the charging cable (saving weight, cost, and simplifying installation). Furthermore, by additionally operating the voltage converter, the charging power at the battery's nominal voltage can be increased.

[0011] There are no additional costs involved, as only the voltage converter needs to be activated and the total current is calculated, including current control. This can be implemented as a pure software solution or as an operating strategy.

[0012] Embodiments of the invention are explained in more detail below with reference to drawings.

[0013] Showing: Fig. 1 a schematic view of a charging arrangement for charging a high-voltage battery of an electrically powered vehicle, Fig. 2 a schematic view of a simulation example of the charging arrangement, Fig. 3 a schematic view of signal curves determined in the simulation example over time, Fig. 4 a schematic view of an exemplary embodiment of the charging arrangement, Fig. 5 a schematic view of another exemplary embodiment of the charging arrangement, Fig. 6 a schematic view of another exemplary embodiment of the charging arrangement, and Fig. 7 a schematic view of another exemplary embodiment of the charging arrangement.

[0014] Corresponding parts are provided with the same reference numerals in all figures.

[0015] Fig. 1 is a schematic view of a charging arrangement 1 for charging a high-voltage battery 2 of an electrically powered vehicle, for example, a passenger car, a commercial vehicle, or a bus, and a charging station 3, in particular a DC charging station, to which the charging arrangement 1 can be connected for charging the high-voltage battery 2. The high-voltage battery 2 has a nominal battery voltage of, for example, 800 V. The charging arrangement 1 has a first charging path 4 for use in charging the high-voltage battery 2 at a charging station 3, which first charging path delivers a voltage V_EVSE equal to the nominal battery voltage.

[0016] The charging arrangement 1 further comprises a second charging path 5 for use in charging the high-voltage battery 2 at a charging station 3, which supplies a voltage V_EVSE that is lower than the nominal battery voltage, for example 400 V. In the second charging path 5, a voltage converter 6, for example a booster, is arranged, which is configured to raise the lower voltage V_EVSE of the charging station 3 to the level of the nominal battery voltage.

[0017] A galvanically coupled voltage converter with any topology can be used as the voltage converter 6 (including boosting via an electric machine and an inverter for controlling the electric machine). Such voltage converters 6 usually have a bypass contactor 7 for charging at the nominal battery voltage, in particular 800 V. However, galvanically isolated or quasi-isolated DC / DC converters can also be considered as the voltage converter 6. These generally have two bypass contactors 7 for charging at the nominal battery voltage, in particular 800 V. All of these voltage converters 6 have in common that they can be regulated and / or controlled to a specified charging current.

[0018] It is assumed that a component in the first charging path 4 limits the maximum charging current at the nominal battery voltage. The limitation of the charging current is therefore not in the charging station 3 or in the cells of the high-voltage battery 2.

[0019] The aim is to operate the charging arrangement 1 for charging at the nominal battery voltage (e.g. at 800 V) in a current-controlled manner at its maximum current strength and at the same time to enable a second current path, whereby the high-voltage battery 2 can be charged with an additional DC charging current.

[0020] The voltage converter 6 in the second charging path 5 can be operated in addition to the first charging path 4 to increase the charging current at the nominal battery voltage. The voltage gain of the voltage converter 6 is at least almost exactly 1, and the current is regulated to a defined target current. Knowing the maximum current of the first charging path 4, a maximum current can be specified for the charging station 3, which corresponds to the sum of the current via the voltage converter 6 and the maximum current via the first charging path 4. The second charging path 5 of the voltage converter 6 now takes over the current it has impressed itself. The remaining charging current of the charging station 3 flows via the first charging path 4. The total current for charging the high-voltage battery 2 is thus higher by the amount of the current from the voltage converter 6 than it would be without the operation of the voltage converter 6.

[0021] Fig. 2 is a schematic view of a simulation example of the charging arrangement 1.

[0022] A resistor R1 of 50 mOhm is assumed for the first charging path 4. As part of the voltage converter 6, a choke L with a resistor R2 of 100 mOhm representing the ohmic component of the choke L and a diode D are connected in series in the second charging path 5, with the diode D being oriented in the forward direction towards the high-voltage battery 2. Furthermore, a MOSFET T with a body diode is connected between a tap between the choke L and the diode D and a negative high-voltage potential HV-. The MOSFET T is controlled depending on an inductor current I_L flowing through the choke L. The second load path 5 has a series circuit consisting of a resistor R3, R4 and a capacitor C1, C2 leading to the negative high-voltage potential HV- both upstream of the resistor R2 and downstream of the diode D.

[0023] In one example, it is assumed that no more than 500 A may flow through the first charging path 4. The voltage converter 6 is controlled, for example, to a current I_Booster between 290 A and 300 A, i.e., the MOSFET T is closed as soon as the inductor current I_L is less than or equal to 290 A, and the MOSFET T is opened as soon as the inductor current I_L exceeds 300 A. Therefore, the charging station 3, as a current source, is controlled to a current I_EVSE of 790 A so that the current I_800V in the first charging path 4 does not exceed 500 A.

[0024] It can be assumed that the voltage drop across diode D and the resistive components (resistor R2) of choke L are greater than the resistive component (resistor R1) in the first charging path 4. Thus, in parallel operation of both load paths 4, 5, the distribution of the current I_EVSE of charging station 3 would be asymmetrical, with the current I_800V in the first charging path 4 being greater than 500 A and the choke current I_L in voltage converter 6 being less than 300 A. In the example, a resistance of 50 mOhm was assumed in the first charging path 4 and a resistance of 100 mOhm in voltage converter 6, plus a voltage drop of 1.5 V across diode D.

[0025] Fig. 3 is a schematic view of signal curves over time determined in the simulation example.

[0026] Shown from top to bottom are the current I_EVSE of charging station 3 (constant 790 A), the voltage V_EVSE of charging station 3, the current I_800V of the first charging path 4, the choke current I_L, a switching state Gate_MOSFET at a gate of the MOSFET T, a current I_Booster of the second charging path 5 and a battery current I_Batt flowing into the high-voltage battery 2.

[0027] The voltage V_EVSE of charging station 3 is approximately 825 V, which is higher than the nominal voltage of high-voltage battery 2 (800 V). This can be explained by the additional voltage drop across resistor R1 in the first charging path 4 and the voltage drop in choke L of voltage converter 6.

[0028] The current I_Booster of the voltage converter 6 is determined by the inductor current I_L, which is controlled at values ​​between 290 A and 300 A. This results in a current I_800V in the first charging path 4 that exhibits similar current fluctuations to the inductor current I_L of the voltage converter 6, whereby the current fluctuations have the opposite sign, i.e. as the inductor current I_L decreases, the current I_800V in the first charging path 4 increases. In moments when the MOSFET T is activated, no current I_Booster is transferred to the high-voltage battery 2 via the voltage converter 6 (only from the capacitor C2). This is noticeable in the battery current I_Batt of the high-voltage battery 2. When the MOSFET T is closed, the battery current I_Batt drops to the value of the current I_800V in the first charging path 4.

[0029] Fig. Figure 4 is a schematic view of an exemplary embodiment of the charging arrangement 1. The high-voltage potentials HV+, HV- connected to the charging station 3 are each provided with a charging contactor DC_P, DC_N. Furthermore, a bypass contactor 7 for the voltage converter 6 is arranged in the first charging path 4. The battery current I_Batt or charging current limited by the bypass contactor 7 of the voltage converter 6 can be increased by the second charging path 5 via the voltage converter 6.

[0030] Furthermore, a current path SP1 of the voltage converter 6 with the MOSFET T closed, a current path SP2 of the voltage converter 6 with the MOSFET T open (freewheeling choke current I_L) and a current path SP3 via the first charging path 4 are shown.

[0031] Fig. 5 is a schematic view of another exemplary embodiment of the charging arrangement 1. The first charging path 4 in the high-voltage potential HV+ connected to the charging station 3 is provided with a charging contactor DC_P1. The second charging path 5 in the high-voltage potential HV+ connected to the charging station 3 is provided with a charging contactor DC_P2 upstream of the voltage converter 6. The high-voltage potential HV is provided with a charging contactor DC_N. The battery current I_Batt or charging current limited by the charging contactor DC_P1 located in the first charging path 4 can be increased by the second charging path 5 via the voltage converter 6.

[0032] Furthermore, a current path SP1 of the voltage converter 6 with the MOSFET T closed, a current path SP2 of the voltage converter 6 with the MOSFET T open (freewheeling choke current I_L) and a current path SP3 via the first charging path 4 are shown.

[0033] Fig. 6 is a schematic view of another exemplary embodiment of the charging arrangement 1. The high-voltage potentials HV+, HV- connected to the charging station 3 are each provided with a charging contactor DC_P, DC_N. Furthermore, battery-internal contactors HV_P1, HV_N1, HV_P2, HV_N2 are arranged in separate supply lines from the voltage converter 6 and the first charging path 4 for both the positive high-voltage potential HV+ and the negative high-voltage potential HV-. Furthermore, fuses F1, F2 are arranged in one of the supply lines from the voltage converter 6 and the first charging path 4, either for the positive high-voltage potential HV+ or for the negative high-voltage potential HV-. Furthermore, connection plugs can be provided.The internal battery contactors HV_P1, HV_N1, HV_P2, HV_N2, fuses F1, F2, and / or connectors or the first charging path 4 at both high-voltage potentials HV+, HV-, including a cable set, the charging contactors DC_P, DC_N, busbars, and connectors, can be operated at their maximum current. The additional current I_Booster flows via the high-voltage battery connection 2 to the voltage converter 6. This allows the overall DC charging power to be increased. A typical application for a voltage converter 6 with its own battery connection would be when the vehicle's inverter is to be used to boost the DC voltage.

[0034] Furthermore, a current path SP1 of the voltage converter 6 with the MOSFET T closed, a current path SP2 of the voltage converter 6 with the MOSFET T open (freewheeling choke current I_L) and a current path SP3 via the first charging path 4 are shown.

[0035] Fig.7 is a schematic view of another exemplary embodiment of the charging arrangement 1. Internal battery contactors HV_P1, HV_N1, HV_P2, HV_N2 are arranged in separate supply lines from the voltage converter 6 and the first charging path 4, both for the positive high-voltage potential HV+ and for the negative high-voltage potential HV. Furthermore, fuses F1, F2 are arranged in one of the supply lines from the voltage converter 6 and the first charging path 4, either for the positive high-voltage potential HV+ or for the negative high-voltage potential HV-. Furthermore, the supply lines of the first charging path 4 and the second charging path 5 are each separately provided with a charging contactor DC_P1, DC_P2, DC_N1, DC_N2 in both high-voltage potentials HV+, HV- connected to the charging station 3. Furthermore, connection plugs can be provided.

[0036] The internal battery contactors HV_P1, HV_N1, HV_P2, HV_N2, fuses F1, F2, and / or connectors or the first charging path 4 in both high-voltage potentials HV+, HV-, including a cable set, the charging contactors DC_P1, DC_P2, DC_N1, DC_N2, busbars, and connectors can be operated at their maximum current limit when charging at the nominal battery voltage. The high-voltage battery 2 can be additionally charged via the second connection via the voltage converter 6. This allows the overall DC charging power to be increased. A typical application for a voltage converter 6 with its own battery connection would be when the vehicle's inverter is to be used to boost the DC voltage.

[0037] Furthermore, a current path SP1 of the voltage converter 6 with the MOSFET T closed, a current path SP2 of the voltage converter 6 with the MOSFET T open (freewheeling choke current I_L) and a current path SP3 via the first charging path 4 are shown.

[0038] By activating and operating the voltage converter 6 during DC charging at the nominal battery voltage, the charging power can be increased, or alternatively, the current-carrying components in the first charging path 4 can be reduced in their current-carrying capacity by the value of the current I_Booster. This is particularly noticeable in the cable cross-sections of the charging cable, which allows for weight and cost savings and simplifies installation. Furthermore, the voltage converter 6 can be used to increase the charging power at the nominal battery voltage.

[0039] The described solution incurs little or no additional costs. Activating voltage converter 6 and calculating a total current, including current control, can be implemented as a software solution or operating strategy. List of reference symbols 1 loading arrangement 2 high-voltage batteries 3 charging stations 4 first charging path 5 second charging path 6 voltage converters 7 Bypass contactor C1, C2 capacitor D-diode DC_P, DC_P1, DC_P2, DC_N, DC_N1, DC_N2 charging contactor F1, F2 fuse Gate_MOSFET switching state HV_P1, HV_N1, HV_P2, HV_N2 battery internal contactor HV+, HV- high voltage potential I_Batt battery current I_Booster Current I_EVSE electricity I_L choke current I_800V current L throttle R1 to R4 resistance SP1 to SP3 current path T MOSFET V_EVSE voltage

Claims

[1] Method for operating a charging arrangement (1) for charging a high-voltage battery (2) of an electrically powered vehicle at a charging station (3) with direct voltage, wherein the charging arrangement (1) has a first charging path (4) for use when charging at a charging station (3) which supplies a voltage (V_EVSE) equal to a nominal battery voltage of the high-voltage battery (2), wherein the charging arrangement (1) further has a second charging path (5) for use when charging at a charging station (3) which supplies a voltage (V_EVSE) which is lower than the nominal battery voltage, wherein a voltage converter (6) is arranged in the second charging path (5) and is configured to raise the lower voltage (V_EVSE) of the charging station (3) to the level of the nominal battery voltage, characterized bythat the voltage converter (6) in the second charging path (5) is operated in addition to the first charging path (4) when charging at a charging station (3) which supplies a voltage (V_EVSE) equal to the nominal battery voltage, in order to increase the charging current, wherein a voltage gain of the voltage converter (6) is at least almost exactly 1 and a current (I_Booster) in the second charging path (5) is regulated to a defined target current. [2] Method according to claim 1, characterized by that the charging station (3) is given a maximum current which corresponds to the sum of the current (I_Booster) via the voltage converter (6) and a maximum current via the first charging path (4). [3] Method according to claim 2, characterized bythat the maximum current via the first charging path (4) is specified or determined based on a current carrying capacity of at least one component located in the first charging path (4), for example a bypass contactor (7), a charging contactor (DC_P, DC_P1, DC_P2, DC_N, DC_N1, DC_N2), a battery-internal contactor (HV_P1, HV_N1, HV_P2, HV_N2), a fuse (F1, F2), a plug, a cable set or a busbar. [4] Method according to one of the preceding claims, characterized by that a galvanically coupled voltage converter or a booster is used as the voltage converter (6).

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